Design And Simulation Implementation For Energy-Efficient Rings In Green Wireless-Optical Broadband Access Network

Wireless-Optical Broadband Access Network (WOBAN) is a promising solution for the "last mile" broadband access by combing the features of large capacity and high reliability of optical access technology with the features of low expenditure and high flexibility of wireless access technology. Since the access networks play the dominant role in terms of energy consumption in the whole network, it is necessary to study the green WOBAN solutions to reduce their energy consumption. Previous schemes on green WOBAN mostly focused on two aspects. On one hand, the Optical Network Units (ONUs) experiencing low input load are switched into sleep mode, and the affected traffic in the wireless front-end is rerouted by designing effective routing algorithms in network layer. On the other hand, sleep/active mode switching of ONUs is realized by valid frame controlling and scheduling in Media Access Control (MAC) layer. However, most of previous energy-efficient strategies aimed at single-segment WOBAN, where only one Optical Line Terminal (OLT) is deployed, rarely considered the energy-saving approaches in multi-segment WOBAN.In this thesis, we propose an energy-saving scheme based on energy-efficient rings in multi-segment WOBAN, which aims at reduce the energy consumption of the optical backhaul part (that is, Passive Optical Network) in WOBAN. This scheme consists of two steps, that is, fiber ring construction among different segments and energy-efficient scheme design. In the first step, firstly, an Integer Linear Programming (ILP) model of segment clustering problem is formulated, then a Genetic Algorithm (GA) is proposed to get the segment clustering result which has the minimal total fully connected distance among segments in all clusters, next, a Backtracking Algorithm (BA) is applied to obtain the fiber link deployment solution which has the minimal fiber deployment length for all clusters, thus multiple fiber rings which connect different segments by fiber links are constrcuted. In the second step, a heuristic enery-saving algorithm base on sleeping scheme is proposed to determine the low-loaded segment which can be switched into sleep mode under three different types of traffic profile in multi-segment scenario, then the relevant traffic in sleep segments is distributed to the active segments through the fiber ring, finally, the total energy consumption of Passive Optical Networks is minimized by sleeping the energy-intensive devices (i.e., OLTs and ONUs) of light-traffic segments without interrupting the traffic service connection of Internet.To evaluate and test the performances of the proposed algorithms, this thesis develops the simulation and solving for our proposed algorithms and ILP model through the VC++6.0 software and CPLEX 11.0 optimizer, repectively. Results show that our proposed algorithms are effective, which can significantly reduce the energy consumption of PON in WOBAN, while it pays for little extra fiber deployment cost, and it provides certain reference for the construction of the green WOBAN in future.